pokan
Standing dumbfounded with your mouth hanging open, unable to react.
💡Hearing unbelievable news — 'I just stood there pokan.'
突然の発表にぽかんと口を開けていた。
I stood there pokan with my mouth open at the sudden announcement.
The students were ___ speechless at the magic trick.
突然の発表に○○と口を開けていた。